1. Field of the Invention
The present invention relates to the use of combinations of fungicides to control mould and related fungus infestations in grasses. In particular the present invention relates to the used of combinations of dicarboximide and 3-phenyl hydantoin fungicides and their formulations.
2. Description Of Related Art
Fine turfgrass species are grown on golf course greens, fairways and tee boxes, as well as turf farms and many other locations. In northern regions, such as Canada and the northern United States, which are subject to temperate climates in the late summer and early fall and snow conditions in late fall and early winter certain moulds such as dollar spot, Sclerotinia homeocarpa, and snow moulds, such as Microdochium nivale, Typhula incarnata and Typhula ishikariensis, represent a chronic problem for turfgrass growers. If left untreated in the late summer and fall, turfgrass is predisposed to damage caused by Sclerotinia homeocarpa in the late summer and fall and the snow moulds in late fall and over winter to spring. Where the mould infection is extensive, the recovery of the turfgrass can be delayed well into the growing season and seriously affect the ability of the turfgrass to recover, leaving areas of dead patches. Further, turfgrasses weakened or damaged by these moulds are extremely slow to recover in the spring and are often invaded by undesirable opportunistic weedy grass species such as creeping bentgrass (Agrostis palustris) and annual bluegrass (Poa annua).
A typical snow mould prevention program requires a mould inhibiting fungicide to be applied to turfgrass prior to permanent winter snow cover. Typical programs consist of three applications prior to permanent snow cover and an additional application after the snow cover is gone in the spring. Several commercial fungicide products have been approved for use against dollar spot and snow mould species, as will be described below.
Another fungus infection that afflicts turfgrass is dollar spot, a disease of turfgrasses caused by the fungus Sclerotinia homeocarpa. This species attacks most turfgrasses grown in the South. Bentgrass, hybrid bermudagrasses and zoysia are most susceptible to dollar spot. The disease occurs from spring through fall, and is most active during moist periods of warm days (70-85° F.) and cool nights (60° F.) in the spring, early summer and fall.
Rovral Green GT™ (iprodione; 3-(3,5-dichlorophenyl)-N-(1-methylethyl)-2,4-dioxo-1-imidazolidinecaboximide) is a dicarboximide fungicide registered in Canada for pink snow mould control at a rate of 250 ml/100 m2 and for grey snow mould control at a rate of 375 ml/100 m2. Iprodione is a member of the class of 3-phenyl hydantoin compounds described in U.S. Pat. No. 3,755,350 to Sauli. The effectiveness of iprodione to control the spread of snow mould in turfgrasses (especially the grey snow moulds T. incarnata and T. ishikariensis) is highly variable due to the varying amounts of fungus inoculums, the varying length of snow cover under which snow mould inoculums thrive and the varying winter temperatures that exist across the country from year to year. Thus, in order to effectively control against a spectrum of snow moulds a relatively high dose may be required as well as multiple applications.
Compass™ (trifloxystrobin; (αE)-α(methoxyimino)-2-[[[(E)-[1-[3-(trifluoromethylphenyl]ethylidine]-amino]oxy]methyl]benzenacetic acid methyl ester) is an aromatic dioxime fungicide which has been approved for the control of leaf spot, Fusarium patch and brown patch diseases in turfgrass. Trifloxystrobin is a member of the class of aromatic dioxime fungicides described in U.S. Pat. No. 5,238,956 granted to Clough et al.